East Asia: Intense water surpluses forecast for southern China

26 October 2018

THE BIG PICTURE
The 12-month forecast for East Asia through June 2019 indicates widespread intense surpluses for Northeast China in Heilongjiang, Jilin, and northern Inner Mongolia; along the Ordos Loop and Upper Reaches of the Yellow River; in Qinghai and Sichuan; and in Tibet, including along the Yarlung River (Brahmaputra). Surpluses of somewhat lesser intensity are forecast for the Pearl River watershed in the south.

Severe deficits are forecast for western Inner Mongolia and Xinjiang along with conditions of both deficit and surplus as transitions occur. Primarily moderate deficits are forecast for central provinces including Shanxi, Henan, and Hubei.

In Japan, surpluses are forecast for southern Honshu and Kyushu, and in western Hokkaido. Deficits are expected around Fukushima. Some moderate deficits are forecast for South Korea. A patchwork of anomalies is forecast for Mongolia with surpluses along rivers in the north and pockets of deficit scattered across the south.

FORECAST BREAKDOWN
The 3-month time series maps below show the evolving conditions in more detail.

Immediately apparent in the October through December forecast is the emergence of widespread surpluses south of the Yangtze River and through much of the Pearl River watershed. Surpluses may be exceptional at the intersection of Guizhou, Hunan, and Guangxi. Widespread surpluses will persist in Sichuan, Qinghai, and Tibet. Deficits are expected to increase and intensify from western Inner Mongolia through Xinjiang, with conditions of both deficit and surplus in areas of transition. Moderate to severe deficits will emerge from the North China Plain to the Yangtze River. Deficits are forecast for Taiwan.

Extreme surpluses are forecast for southern Japan, but some pockets of intense deficit are expected in Hokkaido. On the Korean Peninsula, moderate to severe deficits are forecast for southern North Korea reaching into South Korea. Deficits of varying intensity are expected spanning southern Mongolia and surpluses are forecast along rivers in the north.

From January through March widespread surpluses will persist from the Yantgze south; in Northeast China; and in Qinghai, Sichuan, and Tibet. Widespread deficits will persist from western Inner Mongolia through Xinjiang reaching extreme or exceptional intensity and will re-emerge in some areas where both surplus and deficit were forecast in prior months. Deficits will also persist from the North China Plain to the Yantgze, with intensity increasing to severe in the Plain. Conditions on the Korean Peninsula and in Japan will transition to near-normal, and anomalies in Mongolia will remain much the same as in the forecast for the prior three months with some increase in deficits.

The forecast for the final three months – April through June – indicates that conditions south of the Yangtze will normalize overall, with some surpluses persisting in the western Pearl River region. Surpluses in Qinghai, Sichuan, and Tibet will downgrade somewhat but remain widespread, as will deficits in Inner Mongolia and Xinjiang. Some deficits are forecast for Japan but nearly normal conditions are expected in Korea.

(It should be noted that forecast skill declines with longer lead times.)

IMPACTS
Typhoon Jebi hit western Japan in early September as the strongest typhoon to hit the Japanese mainland in 25 years, killing ten people and injuring more than 400 others. The storm dumped up to 20 inches of rain and caused storm surge which flooded airport runways and part of an airport terminal. High wind gusts smashed a tanker into a bridge connecting Kansai Airport with the mainland, cancelling hundreds of flights.

In late September, Typhoon Kong Rey weakened from a Category 5 storm before brushing Japan’s Ryukyu Islands and then making landfall in South Korea, killing at least two people. The ninth tropical system to hit Japan since early July, Kong-rey dropped over 15 inches of rain on the Japanese island of Kyushu. Over 60,000 people on the Korean island of Jeju lost power, and hundreds of homes were flooded.

Typhoon Trami struck the western city of Osaka, Japan in early October, killing two people and injuring at least 120. The storm cancelled more than 1,000 flights and cut power to over 750,000 homes.

Typhoon Mangkhut struck the Chinese coast near Jiangmen city in Guangdong Province last month, causing extensive wind damage and 12 feet of storm surge in some places. Over 2.5 million people evacuated in Guangdong and on Hainan Island. Hundreds of people were injured, and over 900 flights were cancelled at Hong Kong International Airport. A Boston-based catastrophe modeling firm estimated insured losses in mainland China, Hong Kong, and Macau to be between $1 billion and $2 billion.

Damages in key banana producing prefectures, resulting in as much as 70 percent crop loss, in Guangdong Province heightened already-rising banana prices in the country. Prices rose from $0.61 per kilo in June to $0.76 per kilo in late September.

NOTE ON ADMINISTRATIVE BOUNDARIES
There are numerous regions around the world where country borders are contested. ISciences depicts country boundaries on these maps solely to provide some geographic context. The boundaries are nominal, not legal, descriptions of each

entity. The use of these boundaries does not imply any judgement on the legal status of any territory, or any endorsement or acceptance of disputed boundaries on the part of ISciences or our data providers.

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